CSS has come a long way since its inception, and 2025 has brought some exciting new features that make web development more efficient, dynamic, and fun. Whether you’re a seasoned developer or just starting out, these new CSS features will help you create stunning, responsive, and user-friendly websites. In this blog, we’ll explore seven new CSS features that you need to know, complete with examples and practical use cases.

Let’s dive in!

1. Light-Dark Mode: Dynamic Theming for All Users

What is Light-Dark Mode?

Light-dark mode is no longer a luxury—it’s a necessity. Users expect websites to adapt to their preferences, whether they’re browsing in a brightly lit room or in the dark. With the new light-dark() function in CSS, you can now create dynamic themes effortlessly.

How Does It Work?

The light-dark() function allows you to define two color values: one for light mode and one for dark mode. The browser automatically switches between them based on the user’s system preferences.

Example:

body {
  background-color: light-dark(white, black);
  color: light-dark(black, white);
}

Output

In this example, the background color will be white in light mode and black in dark mode. Similarly, the text color will switch between black and white.

Why It Matters:

This feature eliminates the need for JavaScript to toggle themes, making your code cleaner and more efficient. It also ensures a seamless user experience across devices.

2. New CSS Pseudo-Class: :user-valid & :user-invalid

What Are These Pseudo-Classes?

Form validation is a critical part of user interaction. The new :user-valid and :user-invalid pseudo-classes allow you to style form inputs based on their validation state after the user interacts with them.

How Do They Work?

• :user-valid: Applies styles when the user input is valid.
• :user-invalid: Applies styles when the user input is invalid.

Example:

input:user-valid {
  border: 2px solid green;
}

input:user-invalid {
  border: 2px solid red;
}

Output

In this example, the input field will have a green border if the input is valid and a red border if it’s invalid.

Why It Matters:

These pseudo-classes provide immediate visual feedback to users, improving the overall user experience and reducing form submission errors.

3. Responsive Layouts with Container Queries What’s New in 2025?

What is Container Queries?

Container queries allow elements to respond to their parent container’s size instead of the viewport, making components more reusable and flexible.

How Does It Work?

You define the start and end sizes, and the browser handles the interpolation.

Example:

.container {
  container-type: inline-size;
  width: 80%;
  margin: auto;
}

.card {
  width: 100%;
}

@container (max-width: 600px) {
  .card {
    flex-direction: column;
  }
}

Output

In this example, the .card layout changes dynamically based on the width of its container

Why It Matters:

Container queries make it easier to build truly modular and reusable components without relying on global media queries.

4. Center Elements the Easy Way with align-content

What is align-content?

Centering elements in CSS has always been a pain point for developers. The new align-content property simplifies this process by providing a straightforward way to center elements both horizontally and vertically. but by 2025, the align-content property has been enhanced to support more complex layouts, such as grids and flexboxes.

How Does It Work?

You can use align-content in combination with justify-content to center elements within a container.

Example:

.container {
  display: flex;
  align-content: center;
  justify-content: center;
  height: 100vh;
}

Output

In this example, the content inside the .container div will be perfectly centered.

Why It Matters:

This feature eliminates the need for hacks like margin: auto or transform: translate, making your code cleaner and more maintainable.

5. Level Up Your CSS with the @property At-Rule

What is the @property At-Rule?

The @property at-rule allows you to define custom CSS properties with specific syntax, inheritance, and initial values. This opens up new possibilities for dynamic styling and animations.

How Does It Work?

You define a custom property using @property and then use it in your styles.

Example:

@property --main-color {
  syntax: '<color>';
  inherits: true;
  initial-value: blue;
}

.box {
  background-color: var(--main-color);
  transition: --main-color 1s;
}

.box:hover {
  --main-color: red;
}

Output

In this example, the box’s background color transitions from blue to red when hovered.

Why It Matters:

This feature gives you more control over custom properties, enabling advanced animations and dynamic styles.

6. Styling List Markers with ::marker What’s New in 2025?

What is ::marker?

The ::marker pseudo-element allows full control over the styling of list markers, including colors, fonts, and even content customization.

How Does It Work?

You define the starting style using @starting-style and then specify the transition.

Example:

ul li::marker {
  color: blue;
  font-size: 1.5rem;
  content: '✔ ';
}

Output

Custom List Markers

• Item One
• Item Two
• Item Three

In this example, list items are styled with custom blue checkmarks instead of default bullets.

Why It Matters:

This feature allows for more creative and visually appealing list designs without requiring extra HTML or JavaScript.

7. Simplify Complex Layouts with Advanced CSS Math

What is Advanced CSS Math?

CSS now supports advanced mathematical functions like min(), max(), and clamp(), making it easier to create responsive and flexible layouts.

How Does It Work?

You can use these functions to define sizes, margins, and other properties dynamically.

Example:

.container {
  width: clamp(300px, 50%, 800px);
  margin: auto;
}

Output

In this example, list items are styled with custom blue checkmarks instead of default bullets, and the markers are bold for better visibility.

Why It Matters:

This feature allows for more visually appealing and brand-consistent list styles without relying on background images or extra HTML elements.

Conclusion

CSS continues to evolve, and these new features are game-changers for web developers. From dynamic theming with light-dark mode to advanced animations with interpolate-size, these tools make it easier than ever to create stunning, user-friendly websites.

By incorporating these features into your workflow, you can streamline your code, enhance user experience, and stay ahead of the curve in web development. So, what are you waiting for? Start experimenting with these new CSS features today!